A detector in a receiver in a data communication system can implement either coherent detection or non-coherent detection. In coherent detection, the detector has knowledge of the phase of the carrier signal, and uses this knowledge to improve detection. In non-coherent detection, the detector does not have such information and must therefore try and cancel out any phase discrepancy (e.g. using a differential detection scheme), or apply other non-coherent detection methods known in the art.
A receiver that performs coherent detection offers many advantages. However, there may be situations in which non-coherent detection is necessary (due to the capabilities of the receiver), or is even preferred over coherent detection. It is therefore desirable to develop communication schemes suitable for use with a non-coherent detector.
In Draft IEEE 802.16m System Description Document, IEEE 802.16m-08/003r1, dated Apr. 15, 2008, it is stated that:
This [802.16m] standard amends the IEEE 802.16 WirelessMAN-OFDMA specification to provide an advanced air interface for operation in licensed bands. It meets the cellular layer requirements of IMT-Advanced next generation mobile networks. This amendment provides continuing support for legacy WirelessMAN-OFDMA equipment.    And the standard will address the following purpose:
i. The purpose of this standard is to provide performance improvements necessary to support future advanced services and applications, such as those described by the ITU in Report ITU-R M.2072.